By turns inquisitive, informational and indulgent, the documentary "My Father and the Man in Black" peels back the curtain on the late country music star Johnny Cash and his longtime manager Saul Holiff, a partnership that saw Cash morph from troublesome addict to international superstar, but which ended in the 1970s. Inspired by a trove of letters, artifacts, audio diaries and recorded phone calls Holiff left behind after his suicide, his son Jonathan has made a film that is smoother at laying out an often tempestuous showbiz relationship than exorcising the filmmaker's own demons about a withholding, alcoholic and intermittently cruel dad.

An especially rocky directorial choice is the extensive use of dramatic reenactments — whether starring Jonathan himself or actors playing his father and Cash. But in nearly every other way, when fortified by the tapes, archival footage and Jonathan's emotional narration, the story of how a tough-willed Canadian Jew helped transform a self-destructive Southern Baptist troubadour into a mythic sensation is fairly mesmerizing.

We learn how Saul played musical matchmaker for Cash and June Carter, engineered the Folsom prison gig, but also couldn't stop a born-again Cash's popularity-sapping, self-financed film of Jesus' life, "The Gospel Road." In the end, despite the clunky mix of narrative formats, "My Father and the Man in Black" makes for an illuminating alternate history of sorts to the Hollywoodized version of Cash's ascendancy in "Walk the Line."